1. Field of the Invention
This invention relates generally to a drill bit for boring holes in wood, Corian, or other materials of similar hardness and, more particularly, to drill bits having peripheral cutting edges, known as brad point drill bits.
2. Description of Prior Art
Drill bits are widely employed for creating holes in wood, Corian, or other materials of similar hardness. Brad point drill bits for producing smooth-walled blind-holes or through-holes are especially well-known in the woodworking industry. Particularly, woodworkers use brad point drill bits to produce smooth bore through-holes or blind-holes for fitting finished wood pieces together (for example, by doweling). It is also well-known in the woodworking industry to introduce into bored blind-holes an adhesive material such as glue for securing a dowel within the bore.
Prior art drill bits, in general, have at their tip a pointed center portion which is the first element of the drill bit to engage a workpiece surface. A typical prior art drill bit, which has a spur located peripherally around the pointed center portion at the tip of the drill bit is illustrated in U.S. Pat. No. 4,050,841 to Hildebrandt. The disadvantage of this arrangement is that these center portions have a tendency to walk until the drill bit tip can establish penetration into the surface of the workpiece. Consequently, the precision of the hole location can be compromised, or the workpiece surface can be damaged.
Another disadvantage of prior art drill bits, generally, is that cut chips are guided by the cutting edges of the drill bit into narrow spaces defined by the helical grooves on the flute portion of the drill bit shaft or, alternatively, in a cavity at the tip of the drill bit formed between the pointed center portion and peripherally spaced spurs. Chips can accumulate in these spaces and become impacted, making clean-out difficult and time consuming. Additionally, the build-up of chip material in these spaces can damage the tip of the drill bit.
It is therefore an object of this invention to provide a drill bit which, when engaged with the surface of a workpiece, will prevent the tip of the drill bit from walking. It is also an object of this invention to provide a drill bit with peripheral cutting members.
It is a further object of this invention to provide lateral cutting edges, extending from a central cutting edge, to regrind chips produced by the drill bit into smaller particulate matter for easier clean-out from the drill bit shaft.